new file mode 100644
--- /dev/null
+++ b/dc.c
@@ -0,0 +1,43 @@
+/* Copyright 1990-2011, Jsoftware Inc.  All rights reserved. */
+/* License in license.txt.                                   */
+/*                                                                         */
+/* Debug: Function Call Information                                        */
+
+#include "j.h"
+#include "d.h"
+
+
+static F1(jtdfrep){RZ(w); R NOUN&AT(w)?w:lrep(w);}
+
+static SYMWALK(jtdloc,A,BOX,5,2,1,{RZ(*zv++=sfn(0,d->name)); RZ(*zv++=dfrep(d->val));})
+
+static B jtdrow(J jt,DC si,DC s0,A*zv){A fs,q,*qv,y;C c;
+ fs=si->dcf;
+ GA(q,BOX,si->dcx&&si->dcy?2:1,1,0); qv=AAV(q); 
+ if(si->dcx)*qv++=dfrep(si->dcx); 
+ if(si->dcy)*qv++=dfrep(si->dcy);
+ *zv++=sfn(0,si->dca);                     /* 0 name                     */
+ *zv++=sc(si->dcj);                        /* 1 error number             */
+ *zv++=sc(lnumsi(si));                     /* 2 line number              */
+ *zv++=num[ADV&AT(fs)?1:CONJ&AT(fs)?2:3];  /* 3 name class               */
+ *zv++=lrep(fs);                           /* 4 linear rep.              */
+ *zv++=0;                                  /* 5 script name              */
+ *zv++=q;                                  /* 6 argument list            */
+ if(si->dcloc){RZ(y=dloc(si->dcloc)); RZ(*zv++=grade2(y,ope(irs1(y,0L,1L,jthead))));}
+ else         RZ(*zv++=iota(v2(0L,2L)));   /* 7 locals                   */
+ c=si->dcsusp||s0&&DCPARSE==s0->dctype&&s0->dcsusp?'*':' ';
+ RZ(*zv++=scc(c));                         /* 8 * if begins a suspension */
+ R 1;
+}    /* construct one row of function call matrix */
+
+F1(jtdbcall){A y,*yv,z,*zv;DC si,s0=0;I c=9,m=0,*s;
+ ASSERTMTV(w);
+ si=jt->sitop; while(si){if(DCCALL==si->dctype)++m; si=si->dclnk;}
+ GA(z,BOX,m*c,2,0); s=AS(z); s[0]=m; s[1]=c;
+ si=jt->sitop; zv=AAV(z);
+ while(si){if(DCCALL==si->dctype){RZ(drow(si,s0,zv)); zv+=c;} s0=si; si=si->dclnk;}
+ RZ(y=from(scind(irs1(z,0L,1L,jthead)),over(snl(mtv),ace)));
+ yv=AAV(y); zv=5+AAV(z);
+ DO(m, *zv=*yv++; zv+=c;);
+ R z;
+}    /* 13!:13 function call matrix */